GAINESVILLE, Fla. — The number of severe flu cases in North Central Florida has escalated in recent months, and UF Health Shands Hospital has had a striking increase in influenza-related hospitalizations, with more than 150 admissions and a dozen deaths since late October, UF Health and county public health officials reported today.

The trend mirrors patterns the Centers for Disease Control and Prevention is just now noting in multiple cities across the country.

Of particular concern is the number of younger patients susceptible to this strain of the flu, a variant of H1N1, which first surfaced in 2009, officials said.

Nine of the patients who fell ill were then transferred to UF Health Shands Hospital from neighboring counties in North Florida; three were from Alachua County. Although the vast majority of people who get the flu recover, 11 of the patients had not been vaccinated. Five of them were under the age of 40, raising concerns that this year’s influenza strain is especially virulent for younger populations.

“This is a nasty strain, and it’s hitting young people,” said Dr. J. Glenn Morris, interim hospital epidemiologist and director of the University of Florida Emerging Pathogens Institute. “We often tend to think of the flu as something that kills the old and infirmed. But we’re seeing a striking increase in the number of younger patients contracting the flu and we are also seeing increased severity. Somehow this strain has mutated and it doesn’t look like it’s changed for the better.

“Given the severity of flu that we are seeing this year, everyone should be getting a flu shot.”

Experts emphasized that it’s not too late to be vaccinated; area residents who haven’t yet gotten a flu shot can still benefit.

“This is not solely an Alachua County issue but a North Central Florida one,” said Florida Department of Health-Alachua Administrator Paul Myers. “The reason why these patients were transferred to UF Health Shands was because the hospital has the expertise and the resources to give them the best chance at a good health outcome. The Florida Department of Health in Alachua County is working closely with UF Health to address this unusual increase in severe influenza activity. We are aware of the impact influenza is having on hospitals in Alachua County, particularly UF Health Shands. Increases in hospitalizations and the tragic loss of life associated with influenza underscore the need to get vaccinated.

“Importantly, it’s not too late to get the flu vaccine, which is the best way to protect yourself, family and friends from the flu.”

Fortunately, specialized tests performed at the UF Emerging Pathogens Institute indicate the flu strain circulating in the region is susceptible to Tamiflu, the primary drug used to treat influenza, Morris said. Anyone who suspects they have contracted the flu, especially if they have an underlying medical problem, should see their physician to see whether Tamiflu might help, he said.

“We’re on top of it and we’re doing the work that’s necessary to provide optimal care to our patients and to people in this area,” Morris said. “As a major university medical center, UF Health is uniquely positioned to address the needs of these patients. At the Emerging Pathogens Institute, we’re working as rapidly as possible to try to understand why this is such a nasty virus. It takes a major research capacity to conduct those tests.”

Alachua County has benefited from its school-based influenza immunization program, which helps provide protection for people of all ages through the development of “community immunity,” Morris added.

“This does not mean that people can assume they don’t need a flu shot,” he said. “But it does support the idea that when a high percentage of the community is immunized, the risk of flu is reduced.”

The CDC recommends a three-step approach to fighting influenza:

1. Get a flu vaccine at a local pharmacy or your health-care provider’s office.

2. Take everyday preventive actions to stop the spread of germs, such as washing your hands and using hand sanitizer, and covering your nose and mouth when you sneeze or cough. If you do contract the flu, stay home.